If I start off with a full charge battery on my BB Peal 8120 and connect to the internet using the Shark Modem, how long does the phone battery last if my laptop is on battery(usually the laptop gets 2 hours of battery time on its own)? Also, if the laptop is plugged to the wall for power, will be Pearl always have power?

I'm thinking of getting the Shark Modem app(unless you know of something better), what are your feedback on this service in terms of reliability of not having drops?